You may not have had the most interesting childhood in the world, but everyone has had a few memorable experiences. Highlight the best parts when you can. If you live in a big city, for instance, you should realize that many people who grew up in the country have never ridden a subway, walked to school, ridden in a taxi, or walked to a store a few blocks away.
Review your outline again and imagine that is is a web becoming ever more intricate. Every spider web begins with a single supporting thread that anchors all others. Then the spider lays key connecting threads, to which it attaches many, many smaller lines. Watch an animated video of a web being built. Your initial scenes of obstacles and failure make up the supporting threads to which all others in your story web connect.
Create an outline or a graphic organizer of the major topics and ideas you want to cover. For example, you might make a time-order chart -- a chart with event blocks to organize events chronologically. Or, you might draw a cluster web -- a diagram with connected circles -- to divide your autobiography into sections, such as one for relevant background information, one for life-changing events, one for special memories and one for goals and dreams. Focus on reasons why specific events, situations and circumstances were important to you and how they made you feel.